An improved three-dimensional microscope video camera system coupled with an image system and a quantitative method was developed to observe and evaluate dynamic swelling behavior of coal Particles, and to study kinetics of solvent diffusion in coal particles. The proposed system and method were proved to be more effective, more compact, and more economical than the previous proposed orthogonal microscope system. The new system can finally solve the problem of a one-microscope system and an orthogonal two-microscope system caused by orientation of the anisotropic swelling of coal particles with respect to some known frames of reference not being measured. Using the proposed system and quantitative method, it is possible to obtain the solvent swelling data and kinetics data more accurately. Moreover, the proposed system can be used in dynamically observing and evaluating solvent swelling and diffusion kinetics of any samples with an anisotropic feature, three-dimensionally.